Office chairs are customarily supported on four casters each of which comprises a small wheel mounted eccentrically on a spindle. When the chair is moved from one position to another, the caster wheels swing about the spindle axes into alignment with the direction of movement and roll along the floor. If the floor is carpeted, the chair is more difficult to move especially when someone is sitting in the chair and the repeated swinging and rolling movement of the casters soon wears through the floor covering. In order to protect the floor covering, boards of fiber or plastic are provided underneath the chairs. However, these are unsightly and interfere with cleaning. Most stools such as those used for example in drafting offices and most chairs used in the home are not provided with casters. They hence must ordinarily be lifted in order to be moved from one position to another. They can be slid along the floor only with difficulty and with resultant wear of the floor covering. For example when a person wishes to move up to or away from a table he usually moves his chair by a series of jerking, sliding movements. This is hard on the person, the chair and the floor.